Variable condenser for radiocircuits



Feb. 1 1927.

F. w. STEIN VARIABLE CONDENSER FOR RADIOCIRCUITS Filed May 2, 1924Patented Feb. 1, 1927.

FRED WILLIAM s rain,

PATENT orri-ca.

OF ATCHISON, KANSAS.

VARIABLE CONDENSER FOR RADIOCIRCUITS.

Application filed May 2,

This invention relates to electrical condensers and more particularly tothe type adapted for use in connection with radio apparatus;

Asa general object the present invention has in View the provision of acondenser .that is thoroughly practical and efficient in operation andwhich can be economically manufactured in various sizes and in variouscapacities. In that connection it is proposed to provide a constructionthat gives ideal results with oscillating electrical circuits, and whichbecause of the relatively small plates and parts, reduces loss to aminimum.

As a more specific object the invention contemplates a condenser inwhich a plurality of superimposed plates are employed whereby a maximumcapacity may be obtained through the medium of contact plateshavingrelatively small surface areas, thus creating a condenser whichwill have maxi- .mum capacity but which will occupy very LII littlespace.

Another object of the invention is to provide a. condenser with aplurality of spring metal plates and securing the latter one endtorespective terminals and to provide a hand controlled means for minutelyand positively varying the space between said 1 conductor plates inorder to variably control the capacity of the condenser.

' A still further object of the invention is to provide a condenser ofthe character described in which the hand controlled means includes acam which cooperates with the upper-most conductor plate whereby uponmovement of the cam about an arc of 180 the capacity of the condenserwill be varied from minimum to maximum or vice versa.

With the above and other objects in view which will more readily appearas the nature of the invention is better understood, the same consistsin the novel construction, combination and arrangement of partshereinafter more fully described illustrated and claimed. a

Figure 1 is a top plan view of the invention. f

Fig. 2 is aside elevation.

.Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 1.

Like reference characters designate corresponding' parts throughout theseveral figures of the drawings.

-In carrying out the objects of my invention I provide a main panel Awhich is nor- 1924. Serial No. 710,603.

mally vertically disposed and a supporting base 13 which is horizontallydisposed, the latter being supported on the former by means of a bracketC. The panels A and B are made of any suitable insulating material suchas bakelite for instance. Mounted on the supporting bracket B is a.condenser designated generally at D, the capacity of which may bereadily varied from minimum to i'naxiinuln by a hand controlled means E.

The said condenser D consists of a plu rality of superimposed elongatedspring metal conductor plates which in this instance I have indicated asbeing four in number and numbered respectively 5, 6, 7 and 8. Interposedbetween said conductor plates are dielectric strips or members 9, 10and. 11 which may be of mica or other suitable material. These platesand dielectrics are mounted on the supporting panel B and are secured atone end thereto by terminals 12 and 13 respectively, the terminal v12having connection with the con luctor plates 5 and 7 only whereas theterminal 13 has connection with the plates 6 and 8 only. The bottomcondenser plate 5 is flat throughout its length and lies against thesupporting panel B. The condenser plate 6 is arched upwardly asindicated at 14. The free end portion of the conductor plate 7 is curvedupwardly as indicated at 15, and the condenser plate 8 is archedupwardly as indicated at 16. Thus the condenser plates are normallyspaced apart but are capable of being moved towards one another by theapplication of the hand controlled means E.

The hand controlled means E comprise a cam 17 which in this instance isspecifically shown as an eccentric mounted on a shaft 18. The cam 17 isdisposed at a point sub stantially midway between the ends of thecondenser plates, that is, between the fixed ends and the free endsthereof. The shaft 18 is journaled in the main panel A and consequentlythe longitudinal axis of said shaft lies in a plane at right angles tothe longitudinal axis of the condenser D. The shaft 18 is in turnjournale d in a sleeve 19 which is carried by the main panel A and thissleeve has a threaded engagement with the bracket C. The outer end ofthe sleeve 19 is provided with a head 20 which also serves as a spacingelement for a disk 21 fixed to the shaft 18 so as to space that disk adistance removed from the main panel to provide sufiicient clearance forthe bolts 2222 which connect the bracket C to said main panel. The disk21 is in effect a d al and carries a graduated scale on its peripherywhich is adapted to cooperate with a fixed point marked on the mainpanel. In asmuch as the cam 17 is in the nature of an eccentric it willbe readily apparent that to adjust the condenser D from minimum tomaximum capacity or vice versa it is only necessary to oscillate the camthrough an arc of 180, and consequently the scale on the dial 21occupies 180 and is divided into divisions numbering from Zero to 100.Fixed to the outer end of the shaft 18 is a piece 25 having a knurlededge by means of Which the cam 17 may be readily oscillated.

From the foregoing it Will be observed that the condenser comprisesthree or more superimposed spring metal condenser plates which arealternately connected at one end to respective terminals and Which arenormally spaced apart; that dielectrics are arranged intermediate saidplates; that the hand controlled means may be oscillated about an arc of180 to positively move the plates towarcs one another and therebyvariably increase the capacity of the condenser from minimum to maximum;and that upon reverse oscillation of the hand cont-rolling means theinherent spring in the plates will cause the latter to automaticallybecome separated and thereby automatically decrease the capacity of thecondenser in pro portion to the amount the cam 17 is oscillafed.

Without further description it is thought that the features andadvantages of the invention will be readily apparent to those skilled inthe art,rand it Will of course be understood that changes in the form,proportion and minor details of construction may be resorted to, Withoutdeparting from the spirit of the invention and scope of the appendedclaims.

I claim 1. A variable condenser for radio apparatus, a plurality ofsuperposed metallic condenser plates having dielectric memberstherebctween and secured at one end to an insulating base, and a camhaving its axis arranged parallel to the insulating base and adapted tomove said condenser plates together.

A variable condenser for radio apparatus, a plurality of curved springmetal plates arranged in superposed relation and having dielectricmembers therebetween, iiastcnings for connecting corresponding ends oi?alternate plates to an insulated base leaving the opposite ends of thespring plates tree, and a cam having its axis arranged parallel to theaxis of the insulating base and adapted to compress said plates.

In testimony whereof I hereunto atlix my signature.

FRED lVILLIAM STEIN.

